Reactor including iron cores and rectifier, LC filter, and motor drive apparatus including the same

ABSTRACT

A reactor includes a plurality of iron cores and a winding wound on any of the plurality of iron cores; a gap is formed between two iron cores facing against each other; a gap-facing surface of one iron core has an area larger than that of a gap-facing surface of the other iron core.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/843,269, filed Dec. 15, 2017, which claims benefit ofJapanese Patent Application No. 2016-249198, filed Dec. 22, 2016, thedisclosures of these applications are being incorporated herein byreference in their entirety for all purposes.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a reactor including iron cores and arectifier, an LC filter, and a motor drive apparatus including the same.

2. Description of the Related Art

A reactor including iron cores has a winding wound on the iron core,causes magnetic flux to be generated by current flowing through thewinding, and temporarily stores most of magnetic energy, which exists asmagnetic flux, in a gap provided between the iron cores.

For example, in a motor drive apparatus that drives a motor in a machinetool, a forming machinery, a molding machine, an industrial machinery,or various types of robots, AC power supplied from an AC power supplyside is first converted by a rectifier to DC power, and convertedfurther by an inverter to AC power, which is used as a driving power fora motor provided for each drive axis. The scope of application ofreactors in industry is wide, which includes such as an AC reactorprovided on an AC input side of a rectifier, a smoothing reactorprovided on a DC output side of the rectifier, and a reactorconstituting an LC filter on an AC output side of an inverter in a motordrive apparatus.

Conventionally, there have been approaches for storing a lot of magneticenergy using a small number of iron cores and windings. Varioustechniques have been also proposed to reduce eddy-current loss caused byeddy currents generated in a winding by leakage flux near a gap.

For example, as disclosed in Japanese Unexamined Patent Publication(Kokai) No. S55-53404, there is a reactor for storing more magneticenergy, in which an area of a gap provided between iron cores isconfigured to be larger than a cross-sectional area of the iron core byslanting the gap relative to an axial direction of the reactor to makean acute angle. In addition, as disclosed in Japanese Unexamined PatentPublication (Kokai) No. 2008-210998, for example, there has beenproposed a reactor in which a winding is located away from the vicinityof a gap or a winding is not disposed near a gap, in order to reduceeddy-current loss in the winding caused by leakage flux from the gap.

When current flows through the winding wound on the iron cores, magneticflux flows through the iron cores and the gap between the iron cores ofthe reactor, thereby forming a so-called magnetic path. When passing agap, magnetic flux has a characteristic in which it tries to flowinto/out from iron cores on both sides of the gap as vertically aspossible. Accordingly, with a shape of a gap of a conventional reactor,there has been a problem in which leakage flux is easily radiated near agap toward a winding. This problem is described as follows using thereactor disclosed in Japanese Unexamined Patent Publication (Kokai) No.S55-53404 as an example.

FIG. 30A is a diagram for explaining leakage flux in the reactordisclosed in Japanese Unexamined Patent Publication (Kokai) No.S55-53404, and a full sectional view schematically illustrating astructure of the reactor. FIG. 30B is a diagram for explaining leakageflux in the reactor disclosed in Japanese Unexamined Patent Publication(Kokai) No. S55-53404, and a partial sectional view schematicallyillustrating magnetic flux generated in the reactor. As illustrated inFIG. 30A, a reactor 101 disclosed in Japanese Unexamined PatentPublication (Kokai) No. S55-53404 includes a structure in which arecessed iron core 111 and a protruding iron core 112 are provided so asto interpose a gap 120, and windings 113 are wound around the recessediron core 111 and the protruding iron core 112. The recessed iron core111 includes a recessed gap-facing surface 121 as a surface facingagainst the gap 120 while the protruding iron core 112 includes aprotruding gap-facing surface 122 as a surface facing against the gap120. When current flows through the winding 113, magnetic flux isgenerated. In the illustrated example, a case is illustrated, in whichmagnetic flux is generated in a direction of dotted arrows. Through therecessed iron core 111 and the protruding iron core 112 of the reactor101, main flux flows. Most of the magnetic flux flowing perpendicularlyout of the protruding gap-facing surface 122 of the protruding iron core112 flows perpendicularly into the recessed gap-facing surface 121 ofthe recessed iron core 111 while a portion thereof flows perpendicularlyinto a side surface (i.e., a surface different from the recessedgap-facing surface 121) of the recessed iron core 111. The magnetic fluxflowing perpendicularly into the side surface of the recessed iron core111 is leakage flux. Thus, the reactor 101 disclosed in JapaneseUnexamined Patent Publication (Kokai) No. S55-53404 has a problem inwhich a lot of leakage flux is generated.

As a result, in a conventional reactor including a structure where a lotof leakage flux is generated, there has been a problem in which theshape of the winding needs to be larger in order to store more magneticenergy as well as to reduce eddy-current loss, and this inevitablycauses the reactor to be larger.

SUMMARY OF INVENTION

Therefore, there has been a demand for provision of a reactor that cansuppress generation of leakage flux near a gap, store more magneticenergy, and reduce eddy-current loss as well as a rectifier, an LCfilter, and a motor drive apparatus including such reactor.

According to one aspect of the present disclosure, a reactor may includea plurality of iron cores and a winding wound on any of the plurality ofiron cores; a gap is formed between two iron cores facing against eachother; a gap-facing surface of one of the iron cores has an area largerthan that of a gap-facing surface of the other iron core.

Herein, the respective iron cores may be configured to be in contactwith each other at a region other than the gap-facing surfaces or formedintegrally.

Further, the plurality of iron cores may include a first iron corehaving a first gap-facing surface and a second iron core having a secondgap-facing surface as a surface facing against the first gap-facingsurface, and the winding may be wound on one of the first iron core andthe second iron core or both thereof, and a portion of the firstgap-facing surface near an outer edge thereof of the first iron core andan axial direction may form an acute angle on an inner side of the firstiron core, and a portion of the second gap-facing surface near an outeredge thereof of the second iron core and an axial direction may form anobtuse angle on an inner side of the second iron core, and the firstgap-facing surface may be configured to have a larger area than thesecond gap-facing surface.

Further, a gap may be formed between the iron cores disposed side byside with each other in a substantially circumferential direction, andeach of the iron cores may be provided with a first gap-facing surface,which faces against an iron core disposed side by side with the ironcore concerned on one side, and a second gap-facing surface, which facesagainst an iron core disposed side by side with the iron core concernedon the other side, and, in two of the iron cores disposed side by sidewith each other, the first gap-facing surface of one of the iron coresmay face against the second gap-facing surface of the other iron core,and the first gap-facing surface may be configured to have a larger areathan the second gap-facing surface.

Further, the plurality of iron cores may include a plurality of firstiron cores each having two first gap-facing surfaces and a plurality ofsecond iron cores each having two second gap-facing surfaces as surfacesfacing against the first gap-facing surfaces, and the first iron coresmay be disposed side by side with each other in a substantiallycircumferential direction, and the second iron cores may be disposedside by side with each other in a substantially circumferentialdirection such that each of the second gap-facing surfaces of the secondiron core concerned faces against one of the first gap-facing surfacesof the first iron cores adjacent to the second iron core concerned, andthe winding may be wound on the second iron cores, and either the firstgap-facing surface or the second gap-facing surface may have an arealarger than the other.

Further, the plurality of iron cores may include a plurality of secondiron cores each having two second gap-facing surfaces and a first ironcore having first gap-facing surfaces, the number of which correspond tothe total number of the second gap-facing surfaces of the plurality ofsecond iron cores, and the second iron cores may be disposed side byside with each other in a substantially circumferential direction suchthat each of the second gap-facing surfaces of the second iron coreconcerned faces against one of the first gap-facing surfaces of thefirst iron core, and the winding may be wound on the second iron core,and either the first gap-facing surface or the second gap-facing surfacemay have an area larger than the other.

Further, the first gap-facing surface may include a recessed shape whilethe second gap-facing surface may include a protruding shape.

Further, recessed shapes and protruding shapes, the number of which isone less than that of the recessed shapes, may be formed alternately inthe first gap-facing surface, and recessed shapes and protruding shapes,the number of which is one greater than that of the recessed shapes, maybe formed alternately in the second gap-facing surface.

Further, a bottom portion of the recessed shape may include a curvedshape and a top portion of the protruding shape may include a curvedshape.

In a rectifier according to one aspect of the present disclosure, theaforementioned reactor may be provided as an AC reactor on an AC inputside of the rectifier or a smoothing reactor on a DC output side of therectifier.

In an LC filter according to one aspect of the present disclosure, theaforementioned reactor may be provided as a reactor constituting the LCfilter.

In a motor drive apparatus according to one aspect of the presentdisclosure, the aforementioned reactor may be provided as at least oneof an AC reactor on an AC input side of a rectifier for converting ACpower input from an AC power supply to DC power, a smoothing reactor ona DC output side of the rectifier, and a reactor constituting an LCfilter on an AC output side of an inverter for converting DC poweroutput from the rectifier to AC power for driving a motor.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more clearly understood by reference tothe following accompanying drawings:

FIG. 1A is a diagram illustrating a reactor according to a firstembodiment of the present disclosure, and a full sectional viewschematically illustrating a structure of the reactor;

FIG. 1B is a diagram illustrating the reactor according to the firstembodiment of the present disclosure, and a partial sectional viewschematically illustrating magnetic flux generated in the reactor;

FIG. 2 is a perspective view of the reactor according to the firstembodiment of the present disclosure, illustrated in FIG. 1A and FIG.1B, when a leg portion thereof is a cylindrical reactor;

FIG. 3 is a perspective view of the reactor according to the firstembodiment of the present disclosure, illustrated in FIG. 1A and FIG.1B, when a leg portion thereof is a square reactor;

FIG. 4A is a diagram for explaining the reactor according to the firstembodiment of the present disclosure, illustrated in FIG. 1A and FIG.1B, and a reactor disclosed in Japanese Unexamined Patent Publication(Kokai) No. S55-53404 in comparison with each other, and a partialsectional view schematically illustrating magnetic flux generated in thereactor according to the first embodiment of the present disclosure,illustrated in FIG. 1A and FIG. 1B;

FIG. 4B is a diagram for explaining the reactor according to the firstembodiment of the present disclosure, illustrated in FIG. 1A and FIG.1B, and the reactor disclosed in Japanese Unexamined Patent Publication(Kokai) No. S55-53404 in comparison with each other, and a partialsectional view schematically illustrating magnetic flux generated in thereactor disclosed in Japanese Unexamined Patent Publication (Kokai) No.S55-53404;

FIG. 5A is a diagram illustrating a reactor according to a secondembodiment of the present disclosure, and a full sectional viewschematically illustrating a structure of the reactor;

FIG. 5B is a diagram illustrating a reactor according to the secondembodiment of the present disclosure, and a partial sectional viewschematically illustrating magnetic flux generated in the reactor;

FIG. 6A is a diagram illustrating a simulation result of a magnetic fluxdensity in the reactor according to the first embodiment of the presentdisclosure, and a diagram for explaining change in magnetic flux densityassociated with a variation of the shape of a gap;

FIG. 6B is a diagram illustrating a simulation result of a magnetic fluxdensity in the reactor according to the first embodiment of the presentdisclosure, and a diagram for explaining change in magnetic flux densityassociated with a variation of the shape of a gap under a conditionwhere inductance is constant;

FIG. 6C is a diagram illustrating a simulation result of a magnetic fluxdensity in the reactor according to the first embodiment of the presentdisclosure, and a diagram for explaining change in magnetic flux densitynear a gap associated with a variation of the shape of a gap under acondition where inductance is constant;

FIG. 7A is a diagram illustrating a simulation result of a magnetic fluxdensity in the reactor according to the second embodiment of the presentdisclosure, and a diagram for explaining change in magnetic flux densityassociated with a variation of the shape of a gap;

FIG. 7B is a diagram illustrating a simulation result of a magnetic fluxdensity in the reactor according to the second embodiment of the presentdisclosure, and a diagram for explaining change in magnetic flux densityassociated with a variation of the shape of a gap under a conditionwhere inductance is constant;

FIG. 7C is a diagram illustrating a simulation result of a magnetic fluxdensity in the reactor according to the second embodiment of the presentdisclosure, and a diagram for explaining change in magnetic flux densitynear a gap associated with a variation of the shape of a gap under acondition where inductance is constant;

FIG. 8A is a diagram illustrating a simulation result of a magnetic fluxdensity in the reactor according to an invention disclosed in JapaneseUnexamined Patent Publication (Kokai) No. S55-53404, and a diagram forexplaining change in magnetic flux density associated with a variationof the shape of a gap;

FIG. 8B is a diagram illustrating a simulation result of a magnetic fluxdensity in the reactor according to the invention disclosed in JapaneseUnexamined Patent Publication (Kokai) No. S55-53404, and a diagram forexplaining change in magnetic flux density associated with a variationof the shape of a gap under a condition where inductance is constant;

FIG. 8C is a diagram illustrating a simulation result of a magnetic fluxdensity in the reactor according to the invention disclosed in JapaneseUnexamined Patent Publication (Kokai) No. S55-53404, and a diagram forexplaining change in magnetic flux density near a gap associated with avariation of the shape of a gap under a condition where inductance isconstant;

FIG. 9 is a diagram illustrating observation points of a magnetic fluxdensity in the reactor in the simulation analysis;

FIG. 10 is a partial sectional view illustrating a reactor according toa third embodiment of the present disclosure;

FIG. 11 is a partial sectional view illustrating a reactor according toa fourth embodiment of the present disclosure;

FIG. 12 is a partial sectional view illustrating a reactor according toa fifth embodiment of the present disclosure;

FIG. 13 is a partial sectional view illustrating a reactor according toa sixth embodiment of the present disclosure;

FIG. 14 is a partial sectional view illustrating a reactor according toa seventh embodiment of the present disclosure;

FIG. 15 is a partial sectional view illustrating a reactor according toan eighth embodiment of the present disclosure;

FIG. 16A and FIG. 16B are full sectional views illustrating a reactoraccording to a ninth embodiment of the present disclosure;

FIG. 17A is a view illustrating a reactor according to a tenthembodiment of the present disclosure;

FIG. 17B is a view illustrating the reactor according to the tenthembodiment of the present disclosure, and an enlarged sectional view ofa portion enclosed in the long dashed double-dotted line in FIG. 17A;

FIG. 18 is a full sectional view illustrating a reactor according to aneleventh embodiment of the present disclosure;

FIG. 19A is a full sectional view illustrating a reactor according to atwelfth embodiment of the present disclosure, and illustrates an examplein which a winding is wound on all iron cores;

FIG. 19B is a full sectional view illustrating the reactor according tothe twelfth embodiment of the present disclosure, and illustrates anexample in which a winding is wound on some of the iron cores;

FIG. 20A is a full sectional view illustrating a reactor according to athirteenth embodiment of the present disclosure, and illustrates anexample in which a winding is wound on all iron cores;

FIG. 20B is a full sectional view illustrating the reactor according tothe thirteenth embodiment of the present disclosure, and illustrates anexample in which a winding is wound on some of the iron cores;

FIG. 21A is a full sectional view illustrating a reactor according to afourteenth embodiment of the present disclosure;

FIG. 21B is a view illustrating the reactor according to the fourteenthembodiment of the present disclosure, and an enlarged sectional view ofa portion enclosed in the long dashed double-dotted line in FIG. 21A;

FIG. 22A is a full sectional view illustrating a reactor according to afifteenth embodiment of the present disclosure;

FIG. 22B is a view illustrating the reactor according to the fifteenthembodiment of the present disclosure, and an enlarged sectional view ofa portion enclosed in the long dashed double-dotted line in FIG. 22A;

FIG. 23 is a full sectional view illustrating a variation example of thereactor according to the tenth embodiment of the present disclosure;

FIG. 24 is a full sectional view illustrating a variation example of thereactor according to the eleventh embodiment of the present disclosure;

FIG. 25A is a full sectional view illustrating a variation example ofthe reactor according to the twelfth embodiment of the presentdisclosure, and illustrates an example in which a winding is wound onall iron cores;

FIG. 25B is a full sectional view illustrating a variation example ofthe reactor according to the twelfth embodiment of the presentdisclosure, and illustrates an example in which a winding is wound onsome of the iron cores;

FIG. 26A is a full sectional view illustrating a variation example ofthe reactor according to the thirteenth embodiment of the presentdisclosure, and illustrates an example in which a winding is wound onall iron cores;

FIG. 26B is a full sectional view illustrating a variation example ofthe reactor according to the thirteenth embodiment of the presentdisclosure, and illustrates an example in which a winding is wound onsome of the iron cores;

FIG. 27 is a full sectional view illustrating a variation example of thereactor according to the fourteenth embodiment of the presentdisclosure;

FIG. 28 is a full sectional view illustrating a variation example of thereactor according to the fifteenth embodiment of the present disclosure;

FIG. 29 is a diagram illustrating a motor drive apparatus including areactor according to one aspect of the present disclosure;

FIG. 30A is a diagram for explaining leakage flux in the reactoraccording to the invention disclosed in Japanese Unexamined PatentPublication (Kokai) No. S55-53404, and a full sectional viewschematically illustrating a structure of the reactor; and

FIG. 30B is a diagram for explaining leakage flux in the reactoraccording to the invention disclosed in Japanese Unexamined PatentPublication (Kokai) No. S55-53404, and a partial sectional viewschematically illustrating magnetic flux generated in the reactor.

DETAILED DESCRIPTION

Next, embodiments of the present disclosure will be described withreference to the drawings. To facilitate understanding, scales arechanged in the following drawings as appropriate. Embodimentsillustrated in the drawings are merely examples for implementing oneaspect of the present disclosure, and the present disclosure is notlimited to the embodiments.

In the present description, “axial direction” refers to a direction ofmain flux flowing through an iron core of a reactor. In the presentdescription, when there is a description as “inner one of angles formedbetween a portion of a surface near an outer edge thereof and an axialdirection” with respect to each of a first gap-facing surface and asecond gap-facing surface, it means a minor angle of two angles formedby a portion of the surface concerned near an outer edge thereof and anaxial direction on the axial center side, not a major angle. In thepresent description, it may be understood that a minor angle has thesame meaning as a so-called interior angle.

A reactor according to one aspect of the present disclosure includes aplurality of iron cores and a winding wound on any of the plurality ofiron cores. Between two iron cores facing against each other, a gap isformed, and a gap-facing surface of one of the iron cores has an arealarger than that of a gap-facing surface of the other iron core.Hereinafter, specific configurations will be described with respect tofirst to fifteenth embodiments.

FIG. 1A is a diagram illustrating a reactor according to the firstembodiment of the present disclosure, and a full sectional viewschematically illustrating a structure of the reactor. FIG. 1B is adiagram illustrating the reactor according to the first embodiment ofthe present disclosure, and a partial sectional view schematicallyillustrating magnetic flux generated in the reactor. FIG. 2 is aperspective view of the reactor according to the first embodiment of thepresent disclosure, illustrated in FIG. 1A and FIG. 1B, when a legportion thereof is a cylindrical reactor while FIG. 3 is a perspectiveview of the reactor according to the first embodiment of the presentdisclosure, illustrated in FIG. 1A and FIG. 1B, when a leg portionthereof is a square reactor.

A reactor 1 according to the first embodiment of the present disclosureincludes a first iron core 11, a second iron core 12, and windings 13.Between the first iron core 11 and the second iron core 12, which faceagainst each other, a gap 20 is formed.

The first iron core 11 includes a first gap-facing surface 21 as asurface facing against the gap 20 formed between the first iron core 11and the second iron core 12. A portion of the first gap-facing surface21 near an outer edge thereof of the first iron core 11 and an axialdirection form an acute angle on the inner side of the first iron core11. In other words, the inner one of angles formed by a portion of thefirst gap-facing surface 21 near an outer edge thereof and the axialdirection being an acute angle causes the first gap-facing surface 21 tohave a structure in which the portion thereof near the outer edge isinclined relative to the axial direction at an acute angle.

The second iron core 12 includes a second gap-facing surface 22 as asurface facing against the first gap-facing surface 21 of the first ironcore 11 with the gap 20 interposed therebetween. A portion of the secondgap-facing surface 22 near an outer edge thereof of the second iron core12 and an axial direction form an obtuse angle on the inner side of thesecond iron core 12. In other words, the inner one of angles formed by aportion of the second gap-facing surface 22 near an outer edge thereofand the axial direction being an obtuse angle causes the secondgap-facing surface 22 to have a structure in which the portion thereofnear the outer edge is inclined relative to the axial direction at anobtuse angle. In the illustrated example, the first gap-facing surface21 of the first iron core 11 includes a recessed shape while the secondgap-facing surface 22 of the second iron core 12 includes a protrudingshape.

Note that the first iron core 11 and the second iron core 12 may be incontact with each other at a region other than the first gap-facingsurface 21 and the second gap-facing surface 22 or may be formedintegrally.

The winding 13 is wound on either the first iron core 11 or the secondiron core 12 or both thereof while the winding 13 is wound on the firstiron core 11 and the second iron core 12 in the illustrated example.When the winding is wound on both, the winding may be split near a gapas illustrated in FIG. 16B.

In the reactor 1 according to the first embodiment of the presentdisclosure, the first gap-facing surface 21 of the first iron core 11 isconfigured to have a larger area than the second gap-facing surface 22of the second iron core 12. In other words, the first iron core 11 andthe second iron core 12 are configured such that an outer peripheraledge formed by a line of intersection of the first gap-facing surface 21of the first iron core 11 and a surface 31 adjacent to the firstgap-facing surface 21 has a length longer than an outer peripheral edgeformed by a line of intersection of the second gap-facing surface 22 ofthe second iron core 12 and a surface 32 adjacent to the secondgap-facing surface 22. Thus, as illustrated in FIG. 1A and FIG. 1B, thefirst iron core 11 is configured to include a projection portion 40 nearthe gap 20, and the first iron core 11 around the gap has thicknesslarger than a portion of the first iron core 11 closer to the gapconcerned and the second iron core 12. FIG. 1A and FIG. 1B illustrate anexample of the aforementioned configuration of the first iron core 11and the second iron core 12. Variations of the aforementionedconfiguration of the first iron core 11 and the second iron core 12 willbe described hereinafter.

FIG. 1B illustrates magnetic flux generated when current flows throughthe winding 13 by dotted arrows. When current flows through the winding13 (not illustrated in FIG. 1B), magnetic flux flows through the firstiron core 11 and the second iron core 12 of the reactor 1 and the gap 20between these iron cores, thereby forming a magnetic path. Since thefirst iron core 11 and the second iron core 12 have higher magneticpermeability than the gap 20, which is non-magnetic, each of themagnetic flux will separate from each other when passing the gap 20 andthus, the magnetic flux density in the gap 20 becomes lower than that inthe iron cores. Furthermore, magnetic flux has a characteristic in whichit tries to flow into/out from the first iron core 11 and the secondiron core 12 as vertically as possible. Consequently, when main fluxflows through the first iron core 11 and the second iron core 12 of thereactor 1, the main flux directed from the second iron core 12 to thefirst iron core 11 requires a larger area than when flowing through thesecond iron core 12; therefore, part of the main flux flows out from notonly the second gap-facing surface, but also from the side surface 32 ofthe second iron core 12, and vertically flows into the surface 31adjacent to the first gap-facing surface 21 of the first iron core 11, asurface adjacent to the surface 31 of the projection portion 40, and theside surface of the first iron core 11. This will be explained infurther detail with reference to FIG. 4A and FIG. 4B.

FIG. 4A is a diagram for explaining the reactor illustrated in FIG. 1Aand FIG. 1B and the reactor disclosed in Japanese Unexamined PatentPublication (Kokai) No. S55-53404 in comparison with each other, and apartial sectional view schematically illustrating magnetic fluxgenerated in the reactor illustrated in FIG. 1A and FIG. 1B. FIG. 4B isa diagram for explaining the reactor illustrated in FIG. 1A and FIG. 1Band the reactor disclosed in Japanese Unexamined Patent Publication(Kokai) No. S55-53404 in comparison with each other, and a partialsectional view schematically illustrating magnetic flux generated in thereactor disclosed in Japanese Unexamined Patent Publication (Kokai) No.S55-53404. In FIG. 4A and FIG. 4B, illustration of the winding 13 isomitted.

In comparing the reactor 1 according to the first embodiment of thepresent disclosure, illustrated in FIG. 1A and FIG. 1B, with a reactor101 disclosed in Japanese Unexamined Patent Publication (Kokai) No.S55-53404, the magnetic flux density in the iron cores (the first ironcore 11, the second iron core 12, the recessed iron core 111, and theprotruding iron core 112) is denoted by B1, the sectional area of ironcores (the first iron core 11, the second iron core 12, the recessediron core 111, and the protruding iron core 112) is denoted by S, thelength of the gap is denoted by Ld, and it is assumed that each of theseparameters is equal in the reactor illustrated in FIG. 1A and FIG. 1Band the reactor disclosed in Japanese Unexamined Patent Publication(Kokai) No. S55-53404. In addition, the magnetic flux density in the gap20 between the first iron core 11 and the second iron core 12 is denotedby B2, and the magnetic flux density in the gap 120 between the recessediron core 111 and the protruding iron core 112 is denoted by B3.

An effective area of the first gap-facing surface 21 and the secondgap-facing surface 22 of the reactor 1 according to the first embodimentof the present disclosure, illustrated in FIG. 1A and FIG. 1B, is givenby 2P(=P*2). For the reactor 101 disclosed in Japanese Unexamined PatentPublication (Kokai) No. S55-53404, an effective area of the gap-facingsurfaces is given by “2P(1−α).” The magnetic flux flowing from a portionnear the outer periphery of the gap-facing surface of the protrudingiron core 112 does not flow into the gap-facing surface of the recessediron core 111. The area of the gap-facing surface of the protruding ironcore 112 from which such magnetic flux not flowing into the gap-facingsurface of the recessed iron core 111 flows out is given by 2Pα.

In the reactor 1 according to the first embodiment of the presentdisclosure, illustrated in FIG. 1A and FIG. 1B, since the magnetic fluxpenetrating through the cross-sectional area S of the first iron core 11or the second iron core 12 is equal to the sum of the magnetic fluxpenetrating through the effective area 2P of the first gap-facingsurface 21 and the second gap-facing surface 22 and the leakage flux,equation 1 holds when the product of the leakage flux times the area ofthe portion where the leakage flux is generated is denoted by X.B1×S=B2×2P+X  (1)

Since the magnetic flux density in the gap is determined by the magneticflux density B1 in the iron core and the gap length Ld, the magneticflux densities B2 and B3 of the gaps may be represented as equation 2.B2=B3  (2)

Therefore, magnetic energy W1 accumulated in the gap 20 of the reactor 1according to the first embodiment of the present disclosure, illustratedin FIG. 1A and FIG. 1B, is represented as equation 3 where the magneticpermeability is μ₀.W1=½×μ₀ ×B2{circumflex over ( )}²×2P×Ld  (3)

In the reactor 101 disclosed in Japanese Unexamined Patent Publication(Kokai) No. S55-53404, since the magnetic flux penetrating through thecross-sectional area S of the recessed iron core 111 or the protrudingiron core 112 is equal to the sum of the magnetic flux penetratingthrough the effective area “2P(1−α)” of the gap-facing surfaces and theleakage flux, equation 4 holds when the product of the leakage fluxtimes the area of the portion where the leakage flux is generated isdenoted by Y.B1×S=B3×2P(1−α)+Y  (4)

As a result, the magnetic energy W2 accumulated in the gap 120 of thereactor 101 disclosed in Japanese Unexamined Patent Publication (Kokai)No. S55-53404 is represented as equation 5 where the magneticpermeability is μ₀.

$\begin{matrix}\begin{matrix}{{W\; 2} = {\frac{1}{2} \times \mu_{0} \times B\; 3^{\bigwedge 2} \times 2\;{P\left( {1 - \alpha} \right)} \times {Ld}}} \\{= {{\frac{1}{2} \times \mu_{0} \times B\; 2^{\bigwedge 2} \times 2P \times {Ld}} - \left( {\frac{\alpha}{2} \times \mu_{0} \times B\; 2^{\bigwedge 2} \times 2P \times {Ld}} \right)}}\end{matrix} & (5)\end{matrix}$

With regard to the magnetic flux densities of the gaps, there is arelation “B2=B3.” Thus, in comparison between equation 3 and equation 5,the magnetic energy accumulated in the gap is larger in the reactor 1according to the first embodiment of the present disclosure, illustratedin FIG. 1A and FIG. 1B than in the reactor 101 disclosed in JapaneseUnexamined Patent Publication (Kokai) No. S55-53404.

A magnetic resistance is represented by a formula “a gap length dividedby a magnetic permeability and an area.” The effective area of the gapof the reactor 1 according to the first embodiment of the presentdisclosure, illustrated in FIG. 1A and FIG. 1B, is larger than that ofthe gap of the reactor 101 disclosed in Japanese Unexamined PatentPublication (Kokai) No. S55-53404, and it is given by “P(1−α)<P.” As aresult, the magnetic resistance is lower in the reactor 1 according tothe first embodiment of the present disclosure, illustrated in FIG. 1Aand FIG. 1B than in the reactor 101 disclosed in Japanese UnexaminedPatent Publication (Kokai) No. S55-53404. In other words, the magneticresistance of the gap of the reactor 1 according to the first embodimentof the present disclosure is lower, and the magnetic flux and themagnetic flux density as well as the inductance can be increased under acondition in which the amount of current is the same. Thus, the smallreactor 1 can be realized.

As described above, in the reactor 1 according to the first embodimentof the present disclosure, by setting the thickness of the first ironcore 11 around the gap to be larger than that of a portion of the firstiron core 11 closer to the gap and that of the second iron core 12, thefirst gap-facing surface 21 is configured to have a larger area than thesecond gap-facing surface 22 (in other words, it is configured such thatthe outer peripheral edge formed by the line of intersection of thefirst gap-facing surface 21 and the surface 31 adjacent to the firstgap-facing surface 21 has a length longer than the outer peripheral edgeformed by the line of intersection of the second gap-facing surface 22and the surface 32 adjacent to the second gap-facing surface 22).

Next, as a second embodiment of the present disclosure, an example willbe described in which the area of the first gap-facing surface 21according to the first embodiment of the present disclosure is enlarged.FIG. 5A is a diagram illustrating a reactor according to the secondembodiment of the present disclosure, and a full sectional viewschematically illustrating a structure of the reactor. FIG. 5B is adiagram illustrating the reactor according to the second embodiment ofthe present disclosure, and a partial sectional view schematicallyillustrating magnetic flux generated in the reactor. As illustrated inFIG. 5A and FIG. 5B, in the second embodiment of the present disclosure,a projection portion 41 is configured by further extending theprojection portion 40 in the first embodiment of the present disclosure,illustrated in FIG. 1A and FIG. 1B. With this configuration, asillustrated in FIG. 5B, magnetic flux N flowing out from a portion of asurface 32 near the gap, of magnetic flux vertically flowing out fromthe surface 32 (i.e., a side surface of a second iron core 12) adjacentto a second gap-facing surface 22 of the second iron core 12, willvertically flow into a first gap-facing surface 21 of a first iron core11. Furthermore, since the projection portion 41 is larger, magneticflux M flowing out from a portion of the surface 32 located farther fromthe portion near the gap will vertically flow into the surface 31adjacent to the first gap-facing surface 21 of the first iron core 11.Thus, since the magnetic flux, which is leakage flux in the firstembodiment, vertically flows into the surface 31 adjacent to the firstgap-facing surface 21 of the first iron core 11 and passes through thefirst iron core 11; therefore, according to the second embodiment of thepresent disclosure, the magnetic flux density in the first iron core 11is higher than that in the first embodiment of the present disclosure.The larger the projection portion 41 (i.e., the larger the area of thefirst gap-facing surface 21 as long as it is up to about 1.5 timeslarger the area of the second gap-facing surface 22), the higher themagnetic flux density in the first iron core 11. Note that, also in thesecond embodiment, the first iron core 11 and the second iron core 12may be in contact with each other at a region other than the firstgap-facing surface 21 and the second gap-facing surface 22 or may beformed integrally.

As described above, since the shapes of the gap-facing surfaces (as wellas the areas of the surfaces) of the reactor according to the firstembodiment of the present disclosure, the reactor according to thesecond embodiment of the present disclosure, and the reactor accordingto the invention disclosed in Japanese Unexamined Patent Publication(Kokai) No. S55-53404 are different, the shapes of the correspondinggaps between iron cores are different. The results of simulation withregard to change in gap lengths in the reactors according to the firstand second embodiments of the present disclosure and the reactoraccording to the invention disclosed in Japanese Unexamined PatentPublication (Kokai) No. S55-53404 will be described using FIG. 6A, FIG.6B, FIG. 6C, FIG. 7A, FIG. 7B, FIG. 7C, FIG. 8A, FIG. 8B, and FIG. 8C.FIG. 9 is a diagram illustrating observation points of the magnetic fluxdensity in the reactor in the simulation analysis. While the reactoraccording to the invention disclosed in Japanese Unexamined PatentPublication (Kokai) No. S55-53404, illustrated in FIG. 30A, is taken asan example in FIG. 9, similar points are also used as observation pointsof the magnetic flux density in the reactors according to the first andsecond embodiments of the present disclosure. Point C indicates anobservation point of the magnetic flux density in the iron core, andpoint D indicates an observation point of the magnetic flux density inthe winding.

FIG. 6A, FIG. 6B, and FIG. 6C are diagrams illustrating simulationresults of the magnetic flux density in the reactor according to thefirst embodiment of the present disclosure; FIG. 6A is a diagram forexplaining change in magnetic flux density associated with a variationof the shape of a gap; FIG. 6B is a diagram for explaining change inmagnetic flux density associated with a variation of the shape of a gapunder a condition where inductance is constant; FIG. 6C is a diagram forexplaining change in magnetic flux density near a gap associated with avariation of the shape of a gap under a condition where inductance isconstant. FIG. 6C illustrates the magnetic flux density of the leakageflux in the winding near the gap in the central leg portion of thereactor illustrated in FIG. 6B by means of isograms. FIG. 7A, FIG. 7B,and FIG. 7C are diagrams illustrating simulation results of the magneticflux density in the reactor according to the second embodiment of thepresent disclosure; FIG. 7A is a diagram for explaining change inmagnetic flux density associated with a variation of the shape of a gap;FIG. 7B is a diagram for explaining change in magnetic flux densityassociated with a variation of the shape of a gap under a conditionwhere inductance is constant; FIG. 7C is a diagram for explaining changein magnetic flux density near a gap associated with a variation of theshape of a gap under a condition where inductance is constant. FIG. 7Cillustrates the magnetic flux density of the leakage flux in the windingnear the gap in the central leg portion of the reactor illustrated inFIG. 7B by means of isograms. FIG. 8A, FIG. 8B, and FIG. 8C are diagramsillustrating simulation results of the magnetic flux density in thereactor according to the invention disclosed in Japanese UnexaminedPatent Publication (Kokai) No. S55-53404; FIG. 8A is a diagram forexplaining change in magnetic flux density associated with a variationof the shape of a gap; FIG. 8B is a diagram for explaining change inmagnetic flux density associated with a variation of the shape of a gapunder a condition where inductance is constant; FIG. 8C is a diagram forexplaining change in magnetic flux density near a gap associated with avariation of the shape of a gap under a condition where inductance isconstant. FIG. 8C illustrates the magnetic flux density of the leakageflux in the winding near the gap in the central leg portion of thereactor illustrated in FIG. 8B by means of isograms.

Table 1 illustrates change in magnetic flux density in the iron coresassociated with variations of the shapes of gaps in FIG. 6A, FIG. 7A,and FIG. 8A as numerical values.

Inductance Magnetic flux density [mH] in iron core [T] FIG. 8A 0.11381.4191 Conventional art FIG. 6A 0.1222 1.4829 First embodiment FIG. 7A0.1245 1.5002 Second embodiment

As already described, the effective area or the gap between iron coresis larger in order of the reactor according to the invention disclosedin Japanese Unexamined Patent Publication (Kokai) No. S55-53404 (FIG.8A), the reactor according to the first embodiment of the presentdisclosure (FIG. 6A), and the reactor according to the second embodimentof the present disclosure (FIG. 7A), it is determined from the figuresand Table 1 that the magnetic flux density in the iron cores increasesas the effective area of the gap between the iron cores increases. Thisis because magnetic flux M flowing out from a portion of the surface 32of one of the iron cores (the second iron core 12) located farther fromthe portion near the gap will be more likely to vertically flow into thesurface adjacent to the gap-facing surface of the other iron core (thefirst iron core 11) as the projection portion 41 is larger (i.e., as thearea of the first gap-facing surface 21 is larger than that of thesecond gap-facing surface 22). In addition, the inductance is higher inorder of the reactor according to the invention disclosed in JapaneseUnexamined Patent Publication (Kokai) No. S55-53404 (FIG. 8A), thereactor according to the first embodiment of the present disclosure(FIG. 6A), and the reactor according to the second embodiment of thepresent disclosure (FIG. 7A). This is because α in equation 5 becomessmaller as the projection portion 41 is larger (i.e., as the area of thefirst gap-facing surface 21 is larger than that of the second gap-facingsurface 22), and thus, the inductance increases.

Table 2 illustrates change in magnetic flux density in the iron coresand change in maximum magnetic flux density in the winding, which areassociated with variations of the shapes of gaps under a condition whereinductance is constant in FIG. 6B and FIG. 6C, FIG. 7B and FIG. 7C, andFIG. 8B and FIG. 8C as numerical values.

Magnetic flux Maximum magnetic density in iron flux density in core [T]winding [T] FIG. 88 and FIG. 8C 1.1325 0.109 Conventional art FIG. 68and FIG. 6C 1.1336 0.064 First embodiment FIG. 78 and FIG. 7C 1.13450.059 Second embodiment

In the simulation of FIG. 6B and FIG. 6C, FIG. 7B and FIG. 7C, and FIG.8B and FIG. 8C, the numbers of turns of the windings and the amount ofcurrent are adjusted such that the magnetic flux density in the ironcores is approximately constant (the inductance is approximatelyconstant) for each reactor. In addition, the dimensions are adjustedsuch that the distances from the projection portion 40 of the iron core11 or a peripheral surface of the iron core 111 to the winding locatedin the vicinity are equal. While the effective area of the gap betweeniron cores are larger in order of the reactor according to the inventiondisclosed in Japanese Unexamined Patent Publication (Kokai) No.S55-53404 (FIG. 8B and FIG. 8C), the reactor according to the firstembodiment of the present disclosure (FIG. 6B and FIG. 6C), and thereactor according to the second embodiment of the present disclosure(FIG. 7B and FIG. 7C) as already described, it is determined from thefigures and Table 2 that the magnetic flux density in the windingdecreases as the effective area of the gap between the iron coresincreases. As is apparent from comparison among FIG. 6C, FIG. 7C, andFIG. 8C, it is determined that a region having a lower magnetic fluxdensity in the winding is larger in the reactor (FIG. 6C) according tothe first embodiment of the present disclosure and the reactor (FIG. 7C)according to the second embodiment of the present disclosure than in thereactor (FIG. 8C) according to the invention disclosed in JapaneseUnexamined Patent Publication (Kokai) No. S55-53404. This is becausemagnetic flux M flowing out from a portion of the surface 32 of one ofthe iron cores (the second iron core 12) located farther from theportion near the gap will be more likely to vertically flow into thesurface adjacent to the gap-facing surface of the other iron core (thefirst iron core 11) as the projection portion 41 is larger (i.e., as thearea of the first gap-facing surface 21 is larger than that of thesecond gap-facing surface 22), and thus, the leakage flux into thewinding decreases.

Next, third to eighth embodiments will be described with reference toFIG. 10 to FIG. 15 as further variations of the shapes of the firstgap-facing surface and the second gap-facing surface according to thefirst and second embodiments described above. In FIG. 10 to FIG. 15,illustration of the winding 13 is omitted.

First, in the third embodiment of the present disclosure, a bottomportion (i.e., recessed portion) of a recessed shape and a top portion(i.e., a projection portion) of a protruding shape, which are formed byslanted surfaces, are configured to include a curved shape in each of afirst gap-facing surface and a second gap-facing surface.

FIG. 10 is a partial sectional view illustrating a reactor according tothe third embodiment of the present disclosure. As an example,description is made with respect to the first gap-facing surface 21 andthe second gap-facing surface 22 in the first embodiment described withreference to FIG. 1A and FIG. 1B; however, the beforementioned oraforementioned embodiments can be applied to gap-facing surfacesaccording to other embodiments, which was described above or will bedescribed hereinafter. As illustrated in FIG. 10, the bottom portion ofthe recessed shape of a first gap-facing surface 21 of a first iron core11 includes a curved shape 51 while the top portion of the protrudingshape of a second gap-facing surface 22 of a second iron core 12includes a curved shape 52.

In fourth to sixth embodiments of the present disclosure, the effectiveareas of the gap-facing surfaces are configured to be larger byincreasing the thickness of the body of one of the iron cores to belarger than that of the body of the other iron core.

FIG. 11 is a partial sectional view illustrating a reactor according tothe fourth embodiment of the present disclosure. FIG. 12 is a partialsectional view illustrating a reactor according to a fifth embodiment ofthe present disclosure. FIG. 13 is a partial sectional view illustratinga reactor according to the sixth embodiment of the present disclosure.In each of the fourth to sixth embodiments, a first gap-facing surface21 is configured to have a larger area than a second gap-facing surface22 by increasing the thickness of the body of a first iron core 11 to belarger than that of the body of a second iron core 12. Note that thethird embodiment is further applied to the reactor 1 according to thefifth embodiment illustrated in FIG. 12 and the reactor 1 according tothe sixth embodiment illustrated in FIG. 13 such that the bottom portionof the recessed shape of the first gap-facing surface 21 includes acurved shape 51 while the top portion of the protruding shape of thesecond gap-facing surface 22 includes a curved shape 52.

The seventh and eighth embodiments of the present disclosure are furthervariations of the gap-facing surfaces.

FIG. 14 is a partial sectional view illustrating a reactor according tothe seventh embodiment of the present disclosure. In the seventhembodiment of the present disclosure illustrated in FIG. 14, an outerperipheral edge formed by the line of intersection of a first gap-facingsurface 21 of a first iron core 11 and a surface 31 adjacent to thefirst gap-facing surface 21 is configured to have a length longer thanan outer peripheral edge formed by the line of intersection of a secondgap-facing surface 22 of a second iron core 12 and a surface 32 adjacentto the second gap-facing surface 22; furthermore, the first gap-facingsurface 21 and the second gap-facing surface 22 are configured toinclude a meandering shape.

FIG. 15 is a partial sectional view illustrating a reactor according tothe eighth embodiment of the present disclosure. In the eighthembodiment of the present disclosure illustrated in FIG. 15, a firstgap-facing surface 21 is configured to have a larger area than a secondgap-facing surface 22; furthermore, the first gap-facing surface 21 andthe second gap-facing surface 22 are configured to include a recessedshape(s) and a protruding shape(s) formed alternately. Morespecifically, in order to configure the first gap-facing surface 21 tohave a larger area than the second gap-facing surface 22, recessedshapes and protruding shapes, the number of which is one less than thatof the recessed shapes, are formed alternately in the first gap-facingsurface 21, and recessed shapes and protruding shapes, the number ofwhich is one greater than that of the recessed shapes, are formedalternately in the second gap-facing surface 22. In an exampleillustrated in FIG. 15, two recessed shapes are formed and oneprotruding shape is formed in the first gap-facing surface 21 while onerecessed shape is formed and two protruding shapes are formed in thesecond gap-facing surface 22. Note that the third embodiment is furtherapplied to the reactor 1 according to the eighth embodiment illustratedin FIG. 15 such that the bottom portion of the recessed shape of thefirst gap-facing surface 21 includes a curved shape 51 while the topportion of the protruding shape of the second gap-facing surface 22includes a curved shape 52.

Note that, also in the third to eighth embodiments described above, thefirst iron core 11 and the second iron core 12 may be in contact witheach other at a region other than the first gap-facing surface 21 andthe second gap-facing surface 22 or may be formed integrally.

Although description has been made for the reactors according to thefirst to eighth embodiments described above when the reactor is athree-phase reactor, a reactor according to one aspect of the presentdisclosure may be implemented as a single-phase reactor. FIG. 16A andFIG. 16B are full sectional views illustrating a reactor according to aninth embodiment of the present disclosure. With regard to the reactor 1according to the ninth embodiment of the present disclosure, which isimplemented as a single-phase reactor, the configuration is, asillustrated in FIG. 16A for example, similar to the three-phase reactoraccording to the first embodiment described with reference to FIG. 1Aand FIG. 1B. In addition, for example, if a portion of a firstgap-facing surface 21 near an outer edge thereof of a first iron core 11and an axial direction form an acute angle on the inner side of thefirst iron core 11, a portion of a second gap-facing surface 22 near anouter edge thereof of a second iron core 12 and an axial direction forman obtuse angle on the inner side of the second iron core 12, and thefirst gap-facing surface 21 of the first iron core 11 is configured tohave a larger area than the second gap-facing surface 22 of the secondiron core 12, a single-phase reactor may then be implemented with astructure other than the one illustrated in FIG. 16A; for example, thereactor may be configured as illustrated in FIG. 16B. Note that, also inthe ninth embodiment, the first iron core 11 and the second iron core 12may be in contact with each other at a region other than the firstgap-facing surface 21 and the second gap-facing surface 22 or may beformed integrally.

Next, variations for realizing a reactor according to one aspect of thepresent disclosure as a prismatic reactor will be described withreference to FIG. 17A to FIG. 2B as tenth to fifteenth embodiments.

FIG. 17A is a full sectional view illustrating a reactor according tothe tenth embodiment of the present disclosure. FIG. 17B is a viewillustrating the reactor according to the tenth embodiment of thepresent disclosure, and an enlarged sectional view of a portion enclosedin the long dashed double-dotted line in FIG. 17A. The reactor 1according to the tenth embodiment of the present disclosure isimplemented as a prismatic three-phase reactor. In the reactor 1according to the tenth embodiment of the present disclosure, asillustrated in FIG. 17A and FIG. 17B, gaps 20 are formed between an ironcore 14-1 and an iron core 14-2, between the iron core 14-2 and an ironcore 14-3, and between the iron core 14-3 and the iron core 14-1,wherein the iron cores are disposed in a substantially circumferentialdirection. In addition, each of the iron cores 14-1, 14-2, and 14-3 isprovided with a first gap-facing surface 21, which faces against an ironcore disposed side by side with the iron core concerned on one side, anda second gap-facing surface 22, which faces against the other iron coredisposed side by side with the iron core concerned on the other side.More specifically, the iron core 14-1 is provided with the firstgap-facing surface 21, which faces against the iron core 14-2 disposedside by side with the iron core concerned 14-1 on one side, and thesecond gap-facing surface 22, which faces against the iron core 14-3disposed side by side with the iron core concerned 14-1 on the otherside. The iron core 14-2 is provided with the first gap-facing surface21, which faces against the iron core 14-3 disposed side by side withthe iron core concerned 14-2 on one side, and the second gap-facingsurface 22, which faces against the iron core 14-1 disposed side by sidewith the iron core concerned 14-2 on the other side. The iron core 14-3is provided with the first gap-facing surface 21, which faces againstthe iron core 14-1 disposed side by side with the iron core concerned14-3 on one side, and the second gap-facing surface 22, which facesagainst the iron core 14-2 disposed side by side with the iron coreconcerned 14-3 on the other side. Thus, in the tenth embodiment of thepresent disclosure, two iron cores disposed side by side with each otherare configured such that the first gap-facing surface 21 of one of theiron cores faces against the second gap-facing surface 22 of the otheriron core and the first gap-facing surface 21 has an area larger thanthe second gap-facing surface 22. The number of iron cores is determinedby the number of poles of the reactor 1. For example, when the number ofpoles is two, the number of iron cores is two; when the number of polesis six, the number of iron cores is six. In the illustrated example, thenumber of poles of the reactor 1 is configured to be 3; however, thenumber of poles does not inherently limit the present embodiment and maybe any other value. Furthermore, the shapes of the iron cores 14-1,14-2, and 14-3 illustrated in FIG. 17A and FIG. 17B are merely examplesand may be any shape as long as the first gap-facing surfaces 21 and thesecond gap-facing surfaces 22 have shapes that satisfy theaforementioned relation. Other embodiments with regard to the number ofpoles and the shapes of the iron cores will be described hereinafterwith reference to FIG. 18 to FIG. 20B. When there are a plurality ofpairs of the first gap-facing surface and the second gap-facing surface,inductance will increase and an effect of reducing leakage flux isexerted if the gap-facing surfaces of at least one pair of iron coreshave shapes that satisfy the aforementioned relation. It would bereadily understood that the effect will be maximal when all pairs of thegap-facing surfaces satisfy the aforementioned relation.

FIG. 18 is a full sectional view illustrating a reactor according to aneleventh embodiment of the present disclosure. The reactor 1 accordingto the eleventh embodiment of the present disclosure is implemented as aprismatic three-phase reactor. When the number of poles of iron core isgreater than the number of phases, a winding 13 is wound on iron cores,the number of which corresponds to the number of phases (or a multiplethereof), of the iron cores. In an example illustrated in FIG. 18, ironcores 61-1, 61-2, 61-3, 61-4, 61-5, and 61-6, which constitute sixpoles, are disposed side by side with each other in a substantiallycircumferential direction, and a winding 13 is wound on three (in theillustrated example, reference numerals 61-2, 61-4, and 61-6) of the sixiron cores since the reactor 1 is implemented as a three-phase reactor.In an example illustrated in FIG. 18, the iron cores 61-1, 61-2, 61-3,61-4, 61-5, and 61-6 are configured to include a first gap-facingsurface 21 and a second gap-facing surface 22, which are formed suchthat the edges thereof become sharper toward the center along a radialdirection. Gaps 20 are formed between the iron core 61-1 and the ironcore 61-2, between the iron core 61-2 and the iron core 61-3, betweenthe iron core 61-3 and the iron core 61-4, between the iron core 61-4and the iron core 61-5, between the iron core 61-5 and the iron core61-6, and between the iron core 61-6 and the iron core 61-1, wherein theiron cores are disposed in a substantially circumferential direction.Each of the iron cores 61-1, 61-2, 61-3, 61-4, 61-5, and 61-6 isprovided with the first gap-facing surface 21, which faces against aniron core disposed side by side with the iron core concerned on oneside, and the second gap-facing surface 22, which faces against theother iron core disposed side by side with the iron core concerned onthe other side. More specifically, the iron core 61-1 is provided withthe first gap-facing surface 21, which faces against the iron core 61-2disposed side by side with the iron core concerned 61-1 on one side, andthe second gap-facing surface 22, which faces against the iron core 61-6disposed side by side with the iron core concerned 61-1 on the otherside. The iron core 61-2 is provided with the first gap-facing surface21, which faces against the iron core 61-3 disposed side by side withthe iron core concerned 61-2 on one side, and the second gap-facingsurface 22, which faces against the iron core 61-1 disposed side by sidewith the iron core concerned 61-2 on the other side. The iron core 61-3is provided with the first gap-facing surface 21, which faces againstthe iron core 61-4 disposed side by side with the iron core concerned61-3 on one side, and the second gap-facing surface 22, which facesagainst the iron core 61-2 disposed side by side with the iron coreconcerned 61-3 on the other side. The iron core 61-4 is provided withthe first gap-facing surface 21, which faces against the iron core 61-5disposed side by side with the iron core concerned 61-4 on one side, andthe second gap-facing surface 22, which faces against the iron core 61-3disposed side by side with the iron core concerned 61-4 on the otherside. The iron core 61-5 is provided with the first gap-facing surface21, which faces against the iron core 61-6 disposed side by side withthe iron core concerned 61-5 on one side, and the second gap-facingsurface 22, which faces against the iron core 61-4 disposed side by sidewith the iron core concerned 61-5 on the other side. The iron core 61-6is provided with the first gap-facing surface 21, which faces againstthe iron core 61-1 disposed side by side with the iron core concerned61-6 on one side, and the second gap-facing surface 22, which facesagainst the iron core 61-5 disposed side by side with the iron coreconcerned 61-6 on the other side. Thus, also in the eleventh embodimentof the present disclosure, similarly to the aforementioned tenthembodiment, two iron cores disposed side by side with each other areconfigured such that the first gap-facing surface 21 of one of the ironcores faces against the second gap-facing surface 22 of the other ironcore and the first gap-facing surface 21 has an area larger than thesecond gap-facing surface 22.

FIG. 19A is a full sectional view illustrating a reactor according to atwelfth embodiment of the present disclosure, and illustrates an examplein which a winding is wound on all iron cores. FIG. 19B is a fullsectional view illustrating the reactor according to the twelfthembodiment of the present disclosure, and illustrates an example inwhich a winding is wound on some of the iron cores. The reactor 1according to the twelfth embodiment of the present disclosure isimplemented as a prismatic single-phase reactor. In an exampleillustrated in FIG. 19A, iron cores 62-1, 62-2, 62-3, and 62-4, whichconstitute four poles, are disposed side by side with each other in asubstantially circumferential direction, and a winding 13 is wound onall iron cores. Gaps 20 are formed between the iron core 62-1 and theiron core 62-2, between the iron core 62-2 and the iron core 62-3,between the iron core 62-3 and the iron core 62-4, and between the ironcore 62-4 and the iron core 62-1, wherein the iron cores are disposed ina substantially circumferential direction. Each of the iron cores 62-1,62-2, 62-3, and 62-4 is provided with a first gap-facing surface 21,which faces against an iron core disposed side by side with the ironcore concerned on one side, and a second gap-facing surface 22, whichfaces against the other iron core disposed side by side with the ironcore concerned on the other side. More specifically, the iron core 62-1is provided with the first gap-facing surface 21, which faces againstthe iron core 62-2 disposed side by side with the iron core concerned62-1 on one side, and the second gap-facing surface 22, which facesagainst the iron core 62-4 disposed side by side with the iron coreconcerned 62-1 on the other side. The iron core 62-2 is provided withthe first gap-facing surface 21, which faces against the iron core 62-3disposed side by side with the iron core concerned 62-2 on one side, andthe second gap-facing surface 22, which faces against the iron core 62-1disposed side by side with the iron core concerned 62-2 on the otherside. The iron core 62-3 is provided with the first gap-facing surface21, which faces against the iron core 62-4 disposed side by side withthe iron core concerned 62-3 on one side, and the second gap-facingsurface 22, which faces against the iron core 62-2 disposed side by sidewith the iron core concerned 62-3 on the other side. The iron core 62-4is provided with the first gap-facing surface 21, which faces againstthe iron core 62-1 disposed side by side with the iron core concerned62-4 on one side, and the second gap-facing surface 22, which facesagainst the iron core 62-3 disposed side by side with the iron coreconcerned 62-4 on the other side. Thus, also in the twelfth embodimentof the present disclosure, similarly to the aforementioned eleventhembodiment, two iron cores disposed side by side with each other areconfigured such that the first gap-facing surface 21 of one of the ironcores faces against the second gap-facing surface 22 of the other ironcore and the first gap-facing surface 21 has an area larger than thesecond gap-facing surface 22. In an example illustrated in FIG. 19B,iron cores 62-1, 62-2, 62-3, and 62-4, which constitute four poles, aredisposed side by side with each other in a substantially circumferentialdirection, and a winding 13 is wound on two (in the illustrated example,reference numerals 62-1 and 62-3) of the four iron cores. Sincecomponents other than these are similar to those illustrated in FIG.19A, the same reference numerals denote the same components, anddetailed description thereof is omitted.

FIG. 20A is a full sectional view illustrating a reactor according to athirteenth embodiment of the present disclosure, and illustrates anexample in which a winding is wound on all iron cores. FIG. 20B is afull sectional view illustrating the reactor according to the thirteenthembodiment of the present disclosure, and illustrates an example inwhich a winding is wound on some of the iron cores. The reactor 1according to the thirteenth embodiment of the present disclosure isimplemented, similarly to the twelfth embodiment described withreference to FIG. 19A and FIG. 19B, as a prismatic single-phase reactor;however, the shapes of the iron cores are different from those of thetwelfth embodiment. In an example illustrated in FIG. 20A, iron cores63-1, 63-2, 63-3, and 63-4, which constitute four poles, are disposedside by side with each other in a substantially circumferentialdirection, and a winding 13 is wound on all iron cores. Gaps 20 areformed between the iron core 63-1 and the iron core 63-2, between theiron core 63-2 and the iron core 63-3, between the iron core 63-3 andthe iron core 63-4, and between the iron core 63-4 and the iron core63-1, wherein the iron cores are disposed in a substantiallycircumferential direction. Each of the iron cores 63-1, 63-2, 63-3, and63-4 is provided with a first gap-facing surface 21, which faces againstan iron core disposed side by side with the iron core concerned on oneside, and a second gap-facing surface 22, which faces against the otheriron core disposed side by side with the iron core concerned on theother side. More specifically, the iron core 63-1 is provided with thefirst gap-facing surface 21, which faces against the iron core 63-2disposed side by side with the iron core concerned 63-1 on one side, andthe second gap-facing surface 22, which faces against the iron core 63-4disposed side by side with the iron core concerned 63-1 on the otherside. The iron core 63-2 is provided with the first gap-facing surface21, which faces against the iron core 63-3 disposed side by side withthe iron core concerned 63-2 on one side, and the second gap-facingsurface 22, which faces against the iron core 63-1 disposed side by sidewith the iron core concerned 63-2 on the other side. The iron core 63-3is provided with the first gap-facing surface 21, which faces againstthe iron core 63-4 disposed side by side with the iron core concerned63-3 on one side, and the second gap-facing surface 22, which facesagainst the iron core 63-2 disposed side by side with the iron coreconcerned 63-3 on the other side. The iron core 63-4 is provided withthe first gap-facing surface 21, which faces against the iron core 63-1disposed side by side with the iron core concerned 63-4 on one side, andthe second gap-facing surface 22, which faces against the iron core 63-3disposed side by side with the iron core concerned 63-4 on the otherside. Thus, also in the thirteenth embodiment of the present disclosure,similarly to the aforementioned twelfth embodiment, two iron coresdisposed side by side with each other are configured such that the firstgap-facing surface 21 of one of the iron cores faces against the secondgap-facing surface 22 of the other iron core and the first gap-facingsurface 21 has an area larger than the second gap-facing surface 22. Inan example illustrated in FIG. 20B, iron cores 63-1, 63-2, 63-3, and63-4, which constitute four poles, are disposed side by side with eachother in a substantially circumferential direction, and a winding 13 iswound on two (in the illustrated example, reference numerals 63-1 and63-3) of the four iron cores. Since components other than these aresimilar to those illustrated in FIG. 20A, the same reference numeralsdenote the same components, and detailed description thereof is omitted.

FIG. 21A is a full sectional view illustrating a reactor according to afourteenth embodiment of the present disclosure. FIG. 21B is a viewillustrating the reactor according to the fourteenth embodiment of thepresent disclosure, and an enlarged sectional view of a portion enclosedin the long dashed double-dotted line in FIG. 21A. The reactor 1according to the fourteenth embodiment of the present disclosure isimplemented as a prismatic three-phase reactor. According to thefourteenth embodiment of the present disclosure, the reactor 1 includesfirst iron cores 15-1, 15-2, and 15-3 each having two first gap-facingsurfaces 21, second iron cores 16-1, 16-2, and 16-3 each having twosecond gap-facing surfaces 22 as surfaces facing against the firstgap-facing surfaces 21, and windings 13. The first iron cores 15-1,15-2, and 15-3 are disposed side by side with each other in asubstantially circumferential direction. The second iron cores 16-1,16-2, and 16-3 are also disposed side by side with each other in asubstantially circumferential direction. As illustrated in FIG. 21A andFIG. 21B, gaps 20 are formed between the first iron core 15-1 and thesecond iron core 16-1, between the second iron core 16-1 and the firstiron core 15-2, between the first iron core 15-2 and the second ironcore 16-2, between the second iron core 16-2 and the first iron core15-3, between the first iron core 15-3 and the second iron core 16-3,and between the second iron core 16-3 and the first iron core 15-1,wherein the iron cores are disposed in a substantially circumferentialdirection. The second iron core 16-1 is disposed such that respectivesecond gap-facing surfaces 22 of the second iron core concerned 16-1face against the first gap-facing surfaces 21 of the first iron core15-1 adjacent to the second iron core concerned 16-1 and the firstgap-facing surfaces 21 of the first iron core 15-2 adjacent to thesecond iron core concerned 16-1 with the gap 20 interposed therebetween.The second iron core 16-2 is also disposed such that respective secondgap-facing surfaces 22 of the second iron core concerned 16-2 faceagainst the first gap-facing surfaces 21 of the first iron core 15-2adjacent to the second iron core concerned 16-2 and the first gap-facingsurfaces 21 of the first iron core 15-3 adjacent to the second iron coreconcerned 16-2 with the gap 20 interposed therebetween. The second ironcore 16-3 is also disposed such that respective second gap-facingsurfaces 22 of the second iron core concerned 16-3 face against thefirst gap-facing surfaces 21 of the first iron core 15-1 adjacent to thesecond iron core concerned 16-3 and the first gap-facing surfaces 21 ofthe first iron core 15-3 adjacent to the second iron core concerned 16-3with the gap 20 interposed therebetween. The windings 13 are wound onthe second iron cores 16-1, 16-2, and 16-3. In the fourteenth embodimentof the present disclosure, either the first gap-facing surface 21 or thesecond gap-facing surface 22 has an area larger than the other. FIG. 21Aand FIG. 21B illustrate, as an example, an embodiment in which the firstgap-facing surface 21 has an area larger than the second gap-facingsurface 22. The numbers of the first iron cores and the second ironcores are determined by the number of poles of the reactor 1. Forexample, when the number of poles is two, each of the numbers of thefirst iron cores and the second iron cores is two; when the number ofpoles is six, each of the numbers of the first iron cores and the secondiron cores is six. In the illustrated example, the number of poles ofthe reactor 1 is configured to be 3; however, the number of poles doesnot inherently limit the present embodiment and may be any other value.Furthermore, the shapes of the first iron cores 15-1, 15-2, and 15-3 andthe second iron cores 16-1, 16-2, and 16-3 illustrated in FIG. 21A andFIG. 21B are merely examples and may be any shape as long as the firstgap-facing surfaces 21 and the second gap-facing surfaces 22 have shapesthat satisfy the aforementioned relation.

FIG. 22A is a full sectional view illustrating a reactor according tothe fifteenth embodiment of the present disclosure. FIG. 22B is a viewillustrating the reactor according to the fifteenth embodiment of thepresent disclosure, and an enlarged sectional view of a portion enclosedin the long dashed double-dotted line in FIG. 22A. The reactor 1according to the fifteenth embodiment of the present disclosure isimplemented as a prismatic three-phase reactor. According to thefifteenth embodiment of the present disclosure, the reactor 1 includessecond iron cores 18-1, 18-2, and 18-3 each having two second gap-facingsurfaces 22, a first iron core 17 having first gap-facing surfaces 21,the number of which correspond to the total number of the secondgap-facing surfaces 22 of the second iron cores 18-1, 18-2, and 18-3(six in an example illustrated in FIG. 22A and FIG. 22B), and windings13. The second iron cores 18-1, 18-2, and 18-3 are disposed side by sidewith each other in a substantially circumferential direction such thateach of the second gap-facing surfaces 22 of the second iron coreconcerned faces against any one of the first gap-facing surfaces 21 ofthe first iron core 17 with a gap 20 interposed therebetween. In otherwords, as illustrated in FIG. 22A and FIG. 22B, gaps 20 are formedbetween the second iron core 18-1 and the first iron core 17, betweenthe second iron core 18-2 and the first iron core 17, and between thesecond iron core 18-3 and the first iron core 17, wherein the secondiron cores are disposed in a substantially circumferential direction.The windings 13 are wound on the second iron cores 18-1, 18-2, and 18-3.In the fifteenth embodiment of the present disclosure, either the firstgap-facing surface 21 or the second gap-facing surface 22 has an arealarger than the other. FIG. 22A and FIG. 22B illustrate, as an example,an embodiment in which the first gap-facing surface 21 has an arealarger than the second gap-facing surface 22. The number of the firstgap-facing surfaces 21 of the first iron core and the number of thesecond iron cores are determined by the number of poles of the reactor1. For example, when the number of poles is two, the number of the firstgap-facing surfaces 21 of the first iron cores is four and the number ofthe second iron cores is two; when the number of poles is six, thenumber of the first gap-facing surfaces 21 of the first iron cores istwelve and the number of the second iron cores is six. In theillustrated example, the number of poles of the reactor 1 is configuredto be 3; however, the number of poles does not inherently limit thepresent embodiment and may be any other value. Furthermore, the shapesof the first iron core 17 and the second iron cores 18-1, 18-2, and 18-3illustrated in FIG. 22A and FIG. 22B are merely examples and may be anyshape as long as the first gap-facing surfaces 21 and the secondgap-facing surfaces 22 have shapes that satisfy the aforementionedrelation.

In variation examples of the tenth to fifteenth embodiments describedabove, the iron cores disposed at the outer circumference may be incontact with each other at a region other than the first gap-facingsurface 21 and the second gap-facing surface 22 or may be formedintegrally, which will be described with reference to FIG. 23 to FIG.28.

FIG. 23 is a full sectional view illustrating a variation example of thereactor according to the tenth embodiment of the present disclosure. Inthe present variation example, the iron cores 14-1, 14-2, and 14-3 ofthe reactor 1 of the tenth embodiment described with reference to FIG.17A and FIG. 17B are configured to be in contact with each other at aregion other than the first gap-facing surface 21 and the secondgap-facing surface 22 or formed integrally to be an iron core 14. Sincecomponents other than these are similar to those illustrated in FIG. 17Aand FIG. 17B, the same reference numerals denote the same components,and detailed description thereof is omitted.

FIG. 24 is a full sectional view illustrating a variation example of thereactor according to the eleventh embodiment of the present disclosure.In the present variation example, the iron cores 61-1, 61-2, 61-3, 61-4,61-5, and 61-6 of the reactor 1 of the eleventh embodiment describedwith reference to FIG. 18 are configured to be in contact with eachother at a region other than the first gap-facing surface 21 and thesecond gap-facing surface 22 or formed integrally to be an iron core 61.Since components other than these are similar to those illustrated inFIG. 18, the same reference numerals denote the same components, anddetailed description thereof is omitted.

FIG. 25A is a full sectional view illustrating a variation example ofthe reactor according to the twelfth embodiment of the presentdisclosure, and illustrates an example in which a winding is wound onall iron cores. FIG. 25B is a full sectional view illustrating avariation example of the reactor according to the twelfth embodiment ofthe present disclosure, and illustrates an example in which a winding iswound on some of the iron cores. In the present variation examples, theiron cores 62-1, 62-2, 62-3, and 62-4 of the reactor 1 of the twelfthembodiment described with reference to FIG. 19A and FIG. 19B areconfigured to be in contact with each other at a region other than thefirst gap-facing surface 21 and the second gap-facing surface 22 orformed integrally to be an iron core 62. Since components other thanthese are similar to those illustrated in FIG. 19A and FIG. 19B, thesame reference numerals denote the same components, and detaileddescription thereof is omitted.

FIG. 26A is a full sectional view illustrating a variation example ofthe reactor according to the thirteenth embodiment of the presentdisclosure, and illustrates an example in which a winding is wound onall iron cores. FIG. 26B is a full sectional view illustrating avariation example of the reactor according to the thirteenth embodimentof the present disclosure, and illustrates an example in which a windingis wound on some of the iron cores. In the present variation examples,the iron cores 63-1, 63-2, 63-3, and 63-4 of the reactor 1 of thethirteenth embodiment described with reference to FIG. 20A and FIG. 20Bare configured to be in contact with each other at a region other thanthe first gap-facing surface 21 and the second gap-facing surface 22 orformed integrally to be an iron core 63. Since components other thanthese are similar to those illustrated in FIG. 20A and FIG. 20B, thesame reference numerals denote the same components, and detaileddescription thereof is omitted.

FIG. 27 is a full sectional view illustrating a variation example of thereactor according to the fourteenth embodiment of the presentdisclosure. In the present variation example, the second iron cores16-1, 16-2, and 16-3 of the reactor 1 of the fourteenth embodimentdescribed with reference to FIG. 21A and FIG. 21B are configured to bein contact with each other at a region other than the first gap-facingsurface 21 and the second gap-facing surface 22 or formed integrally tobe an iron core 16. Since components other than these are similar tothose illustrated in FIG. 21A and FIG. 21B, the same reference numeralsdenote the same components, and detailed description thereof is omitted.

FIG. 28 is a full sectional view illustrating a variation example of thereactor according to the fifteenth embodiment of the present disclosure.In the present variation example, the second iron cores 18-1, 18-2, and18-3 of the reactor 1 of the fifteenth embodiment described withreference to FIG. 22A and FIG. 22B are configured to be in contact witheach other at a region other than the first gap-facing surface 21 andthe second gap-facing surface 22 or formed integrally to be an iron core18. Since components other than these are similar to those illustratedin FIG. 22A and FIG. 22B, the same reference numerals denote the samecomponents, and detailed description thereof is omitted.

The reactor 1 according to each of the above-described embodiments ofthe present disclosure may be used in a motor drive apparatus as atleast one of an AC reactor on an AC input side of a rectifier forconverting AC power supplied from an AC power supply into DC power, asmoothing reactor on a DC output side of the rectifier, and a reactorconstituting an LC filter on an AC output side of an inverter forconverting DC power output by the rectifier into AC power for driving amotor. This will be described more specifically with reference to FIG.29.

FIG. 29 is a diagram illustrating a motor drive apparatus including areactor according to one aspect of the present disclosure. The motordrive apparatus 1000 includes a rectifier 1001, which converts AC powersupplied from an AC power supply 1003 side into DC power, which isoutput to a DC link in which a DC capacitor 1005 is provided, aninverter 1002, which converts the DC power output by the rectifier 1001into AC power for driving a motor, and the motor drive apparatus 1000controls velocity, torque, or a position of a motor 1004 connected to anAC output side of the inverter 1002. The rectifier 1001 includes areactor 1 according to one aspect of the present disclosure on an ACinput side as an AC reactor, and includes the reactor 1 according to oneaspect of the present disclosure on a DC output side as a smoothingreactor. The inverter 1002 includes the reactor 1 according to oneaspect of the present disclosure on an AC output side as a reactorconstituting an LC filter 1006 on the AC output side. In the illustratedexample, the reactor 1 according to one aspect of the present disclosureis used for three types of reactors, i.e., the AC reactor provided onthe AC input side of the rectifier 1001, the smoothing reactor on the DCoutput side of the rectifier 1001, and the reactor constituting the LCfilter 1006 on the AC output side of the inverter 1002; however, thereactor 1 according to one aspect of the present disclosure may not benecessarily used for all of these three types of reactors, and may beused for only one or two of these three types of reactors.

According to one aspect of the present disclosure, a reactor that cansuppress generation of leakage flux near a gap, store more magneticenergy, and reduce eddy-current loss as well as a rectifier, an LCfilter, and a motor drive apparatus including such reactor can berealized.

According to one aspect of the present disclosure, by configuring areactor including a plurality of iron cores and a winding wound on anyof the plurality of iron cores such that a gap-facing surface of one ofthe iron cores has an area larger than that of a gap-facing surface ofthe other iron core in the iron cores disposed side by side with eachother, such reactor can suppress generation of leakage flux near a gap,store more magnetic energy, and reduce eddy-current loss.

The invention claimed is:
 1. A reactor comprising: a plurality of ironcores; and a winding wound on any of the plurality of iron cores;wherein a gap is formed between two of the iron cores facing againsteach other and a gap-facing surface of one of the iron cores has an arealarger than that of a gap-facing surface of the other iron core, whereinthe plurality of iron cores comprise a plurality of second iron coreseach having two second gap-facing surfaces and a first iron core havingfirst gap-facing surfaces, the number of which correspond to the totalnumber of the second gap-facing surfaces of the plurality of second ironcores, wherein the second iron cores are disposed side by side with eachother in a substantially circumferential direction such that each of thesecond gap-facing surfaces of the second iron core concerned facesagainst one of the first gap-facing surfaces of the first iron core,wherein the winding is wound on the second iron core, and wherein eitherthe first gap-facing surface or the second gap-facing surface has anarea larger than the other.
 2. The reactor according to claim 1, whereinthe plurality of iron cores comprise a first iron core having a firstgap-facing surface and a second iron core having a second gap-facingsurface as a surface facing against the first gap-facing surface,wherein the winding is wound on one of the first iron core and thesecond iron core or both thereof, wherein a portion of the firstgap-facing surface near an outer edge thereof of the first iron core andan axial direction form an acute angle on an inner side of the firstiron core, wherein a portion of the second gap-facing surface near anouter edge thereof of the second iron core and an axial direction forman obtuse angle on an inner side of the second iron core, and whereinthe first gap-facing surface is configured to have a larger area thanthe second gap-facing surface.
 3. The reactor according to claim 1,wherein the respective iron cores are configured to be in contact witheach other at a region other than the gap-facing surfaces or formedintegrally.
 4. The reactor according to claim 3, wherein the pluralityof iron cores comprise a first iron core having a first gap-facingsurface and a second iron core having a second gap-facing surface as asurface facing against the first gap-facing surface, wherein the windingis wound on one of the first iron core and the second iron core or boththereof, wherein a portion of the first gap-facing surface near an outeredge thereof of the first iron core and an axial direction form an acuteangle on an inner side of the first iron core, wherein a portion of thesecond gap-facing surface near an outer edge thereof of the second ironcore and an axial direction form an obtuse angle on an inner side of thesecond iron core, and wherein the first gap-facing surface is configuredto have a larger area than the second gap-facing surface.